Code Generation with LINQPad 4

Today I encountered a task at work that offered the prospect of some pretty dull development work–code that needed to be written that was almost the same in multiple cases (but not quite).  It seemed like work that could benefit from the use of T4 templates, but quickly became frustrated by the process of setting up and debugging a template.  The interleaving of angle bracket markup with code was never fun in XML, and T4 templates began to resemble that very quickly.

So after abandoning the T4 template approach, I fired up LINQPad to see if I could accomplish my goal in that.  As it turned out, writing a small C# program in LINQPad for code generation was a lot easier.  I just needed to remember two key things about string substitution in verbatim string literals.  Here they are:

  1. Curly brackets need to be escaped.  So “{” should be “{{” and “}” should be “}}”.  Not doing this will result in a FormatException.
  2. Double quotes need to be escaped.  So ” should be “”.

Beyond that, it was a matter of writing a code template inside a verbatim string literal (@”<code template goes here>”) with format items where needed ({0},{1},…).

I’ve made a code sample available as GitHub gist here.  So far, I’ve used this technique to generate nearly 20 files in a fraction of the time it would have taken to write them manually.  Very little manual tweaking of the files was needed after generation, which left more time to test the generated code in real scenarios.

Book Review: Building Interactive Queries with LINQPad

Any new technical book has the challenge of adding value above and beyond what’s available for free on the web.  A new book on LINQPad has the additional challenge of adding value above and beyond the wealth of samples already included with LINQPad, including code samples from two LINQPad-enabled books.  So when I received my review copy of Building Interactive Queries with LINQPad, I was very curious to see what the author (Sebastien Finot) could accomplish in 126 pages.

Even as someone who has used LINQPad enough in the past few years to present on it on front of a .NET user group, I learned new things about the tool I hadn’t known before (such as the ability to interact with the console and CSS customization of the application’s look-and-feel).  The book might have been more accurately titled “Building Interactive Queries with LINQ and LINQPad”, as the book provided good examples of a wide variety for LINQs query operators.  Finot also mentioned the performance implications of ToList()–a very useful mention depending on the size of collection you might be dealing with in your queries.  All the code samples in the book are available for download as well.

The book missed some opportunities to add value for readers.  Fuller treatment of the NuGet dependency management capabilities in the paid versions of LINQPad would have been helpful in deciding if the feature was worth paying for.  Finot also mentioned the existence of LINQ to Twitter and LINQ to JSON APIs but didn’t link to the projects in the book.  More examples of using LINQ to parse and manipulate JSON (instead of XML) would have improved the book significantly, given the increased usage of JSON in .NET development these days.  Unfortunately, the code samples didn’t include databases, which would have enabled the author to go above and beyond the fairly standard Northwind database examples.  A custom OData feed for use in explaining the ability of LINQPad to query those data sources would have been a great help as well (given the rather tenuous availability of the sample services at

Building Interactive Queries with LINQPad is the only book I’ve seen dealing specifically with LINQPad.  If you use LINQPad on a regular basis (or plan to), the e-book is worth purchasing.  For an in-depth treatment of LINQ, you’ll have to look elsewhere.

Disclosure: I received the e-book free of charge from the publisher for the purpose of providing this review.